1. Field of the Invention
The present invention relates to a sealing member for an electronic component package that includes a first sealing member and an opposing second sealing member to hermetically enclose an electrode of an electronic component element, the sealing member being applicable to the first sealing member. The present invention also relates to an electronic component package that uses the sealing member.
2. Discussion of the Background
The packages of electronic components (hereinafter referred to as electronic component packages) such as piezoelectric resonator devices have their internal spaces hermetically enclosed in order to prevent property degradation of the electrodes of the electronic component elements mounted in the internal spaces.
An electronic component package of this kind includes two sealing members such as a base and a lid. The base and the lid define a package in the form of a rectangular parallelepiped. In the internal space of the electronic component package, an electronic component element such as a piezoelectric resonator plate is bonded to and held by the base. The bonding of the base and the lid hermetically encloses the electrodes of the electronic component element in the internal space of the electronic component package.
For example, Japanese Unexamined Patent Application Publication No. 6-283951 (hereinafter referred to as patent document 1) discloses a crystal component (an electronic component of the present invention) that includes an electronic component package defined by the base and the lid. In the internal space of the electronic component package, a crystal plate is hermetically enclosed. The crystal component includes a base that has through holes passing through the base material of the base. Each through hole includes, on its internal surface, a wiring metal made of a multiple-layer metal film such as Cr—Ni—Au. Each through hole further includes an alloy such as Au—Ge welded therein, thus securing air tightness of the internal space of the electronic component package.
Incidentally, such electronic components are subjected to heat when mounted on boards such as printed circuit boards, which involves the following problems. In the crystal component disclosed in patent document 1, the heat applied to the crystal component when mounted on the board can cause softening (diffusion) of the boundary between the internal surface of the through hole and the alloy attached to the internal surface, degrading the adherence between the alloy and the internal surface of the through hole. The degraded adherence of the alloy causes detachment of the alloy off the internal surface of the through hole, and the detached alloy can drop outside the electronic component package of the crystal component. The dropping of the alloy out of the through hole leads to degraded air tightness of the internal space of the electronic component package.
In order to ensure enough air tightness in the internal space of the electronic component package, the inventor invented a sealing technique of filling the through hole with a conducting material (metal) to serve as a part of the wiring pattern, and of sealing the opening face of the through hole at the side of the other principal surface with a resin material. Unfortunately, a problem arises in that the adhesion strength of the resin with respect to the base can degrade in some cases.
Specifically, a wiring pattern made of metal is disposed on the rear surface (the other principal surface) of the base. Hence, the resin material to hermetically enclose the through hole is disposed not only over the other principal surface (a blank surface) of the base but also over the wiring pattern formed on the other principal surface.
Resin materials (especially highly heat resistant resins, which are highly heat resistant) have weakness in adhesion strength (adhesiveness) with respect to Cu and precious metals (such as Au). Hence, the adhesion strength (adhesiveness) is poor between the resin material and the conducting material, which can cause detachment of the resin material off the conducting material, such as the wiring pattern. This can cause a possibility of degradation of air tightness in the internal space of the electronic component package.
The present invention has been made in view of the above-described circumstances, and it is an object of the present invention to provide a sealing member for an electronic component package that minimizes the degradation of air tightness of the internal space of the electronic component package even when a resin material is adopted on the other principal surface of the sealing member for the electronic component package for the purpose of hermetically enclosing the internal space of the electronic component package, and to provide an electronic component package.